1. Field of the Invention
The present invention relates to a cam mechanism provided partly on a base member and partly on a rotating member so as to permit the rotating member to rotate while shifting its pivoted position. The present invention relates also to a door opening/closing mechanism that permits the opening of a storage compartment of a refrigerator or the like to be opened and closed by the rotation of a rotating member.
2. Description of the Related Art
Conventional door opening/closing mechanisms for hinged double doors have a partition board provided in the middle of an opening of a refrigerator so that a left door and a right door close the opening by making contact with the partition board. The partition board hinders work conducted through the opening. For this reason, some door opening/closing mechanisms do away with such a partition board and use gaskets to fill the gap between the left and right doors.
However, when gaskets are provided there, opening one door causes the gasket provided on that door to rub against the gasket provided on the other door. This rubbing together produces a frictional force, which leads to problems such as a great force required when the doors are opened or closed and breakage of the gaskets.
To solve these problems, Japanese Patent Application Laid-Open No. S60-24390 discloses a door opening/closing mechanism in which, when one door starts opening, it slides away from the other door. This door opening/closing mechanism has a first rotary shaft provided on a bracket provided so as to protrude frontward from a chassis forming the outer walls of an opening.
A lever member is mounted on the bracket, and the first rotary shaft is fitted into a hole formed at one end of the lever member. A second rotary shaft is formed integrally at the other end of the lever member, and a door is pivoted on the second rotary shaft. Moreover, a guide member is provided so that, when the door is opened, the lever member rotates about the first rotary shaft, and a spring is provided to load the lever member with a force that tends to move it back to its original position.
When one door is opened, the lever member rotates by being guided by the guide member and, as the lever member rotates, the door slides over a predetermined distance. This causes the door to move away from the other door. Thereafter, the door moves away from the opening, and the guide member disengages from the lever member, letting the lever member move back to its original position under the force exerted by the spring. Then, the door opens by rotating about the second rotary shaft.
When the door is closed, it approaches the opening by rotating about the second rotary shaft. Thereafter, the guide member starts engaging with the lever member against the force exerted by the spring, letting the lever member rotate about the first rotary shaft, so that the door slides away from the other door. Then, as the door is closed, the lever member, by being guided by the guide member, moves back to its original position under the force exerted by the spring. In this way, the door is closed.
However, in the door opening/closing mechanism disclosed in Japanese Patent Application Laid-Open No. S60-24390 mentioned above, a frictional force commensurate with the weight of the door acts on the surfaces on which the lever member and the bracket slide relative to each other. This requires that the spring be designed to exert a force greater than the frictional force.
As a result, to open the door, a great force is required against the frictional force of the lever member and the force exerted by the spring, leading to poor operability. Moreover, the provision of the lever member and the spring increases the number of parts needed and the number of assembly steps, leading to high cost and low reliability of the door opening/closing mechanism.